Do jamb extensions come in standard sizes?

No, this is a custom jamb made to order, so proper measurement is very important! The minumum jamb extension is 2.5 inches, the maximum is 4 feet.

If a garden window unit has been incorrectly ordered because of jamb, head and seat board sizing, we offer two options:

At the customer’s request, we will re-work the unit to the correct jamb thickness. The customer would be responsible for shipping the unit to Ventana and would incur the costs associated with the re-work.
If that is not feasible, the installer can build out the short existing jambs, head and seat board and overlay them with .25″ plywood veneer. (Although we have supplied white high-pressure laminate in the past, we do not supply veneer.)